Indium-containing dehydrogenation catalyst

ABSTRACT

A new catalyst composition comprising a platinum group component, a tin component, an indium component, an alkali or alkaline earth component and a porous support material wherein the atomic ratio of indium to platinum group component is more than 1.0 is disclosed. The catalyst is particularly useful for dehydrogenating hydrocarbons. In one embodiment of the invention, detergent range normal paraffins (C 10  -C 15  or higher) are dehydrogenated to the corresponding normal olefins in the presence of the subject catalyst and hydrogen.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of prior copendingapplication Ser. No. 318,520 filed Nov. 5, 1981 and now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to the conversion of hydrocarbons, especiallythe dehydrogenation of dehydrogenatable hydrocarbons, in the presence ofa heterogeneous catalyst composite. Dehydrogenatable hydrocarbonscontain at least two non-aromatic adjacent carbon atoms having one ortwo carbon-carbon bonds in common, each carbon atom of the pair havingat least one hydrogen atom bonded to it. A heterogeneous catalyst is onewhich is in a phase different from the phase or phases of the reactantsit catalyzes, for example, a solid catalyst which catalyzes liquid orgaseous reactants.

Dehydrogenating hydrocarbons is an important commercial process becauseof the great demand for dehydrogenated hydrocarbons for the manufactureof various chemical products such as detergents, high octane gasolines,pharmaceutical products, plastics, synthetic rubbers, and other productswell known to those skilled in the art. One example of this process isdehydrogenating normal paraffin hydrocarbons having 2 to 20 or morecarbon atoms per molecule to selectively produce corresponding normalmono-olefins. These normal mono-olefins are important to the detergentindustry, for example, where they are utilized to alkylate an aromaticcompound such as benzene with subsequent transformation of the productarylalkane into compounds for use in a wide variety of biodegradablehousehold and industrial detergents.

2. Description of the Prior Art

Many components have been added to platinum group-containingcompositions to obtain catalysts with improved performance. For example,U.S. Pat. Nos. 2,814,599 and 2,914,464 disclose adding primaryactivating agents selected from the group of gallium, indium, scandium,yttrium, lanthanum, thallium and actinium, and optional secondaryactivating agents selected from the group of mercury, zinc and cadmium,as well as optional promoting agents selected from the alcohols andketones to obtain a platinum and/or palladium catalyst with improvedreforming activity.

U.S. Pat. No. 3,745,112 discloses that tin is a good promoter forplatinum group-containing reforming catalysts. This patent disclosesalso that a platinum-tin-alkali or alkaline earth composite is aparticularly effective catalyst for dehydrogenating hydrocarbons. In thedehydrogenation catalyst composite of this patent the alkali or alkalineearth component is added and the amount of halogen is minimized in orderto eliminate the isomerization and cracking reactions which occur on theacidic catalytic sites.

U.S. Pat. No. 3,892,657 discloses that indium is a good promoter forplatinum group-containing reforming catalysts when the atomic ratio ofindium to platinum is from about 0.1:1 to about 1:1. In column 4, lines10-12, this patent discloses that only when the atomic ratio of indiumto platinum is about 0.1 to 1.0 is the beneficial interaction of indiumwith platinum obtained. In column 25, lines 33-37, this patent disclosesthat when the atomic ratio is 1.35 or more, the beneficial effect ofindium is not obtained. This patent discloses also that a Group IVAcomponent selected from the group of germanium, tin, and lead can beadded to the acidic form of the indiumcontaining catalysts for reformingapplications. The acidic form of this catalyst, then, comprises aplatinum group component, a Group IVA component, an indium component, ahalogen component and a porous carrier material. For dehydrogenationapplications this patent discloses a catalyst comprising a platinumgroup component, an indium component and an alkali or alkaline earthcomponent with the porous carrier material. No catalyst comprisingindium, platinum, tin, and an alkali or alkaline earth component isspecifically disclosed in this patent.

British Pat. No. 1 499 297 discloses a dehydrogenation catalystcomprising platinum, at least one of the elements gallium, indium andthallium, and an alkali metal, especially lithium or potassium, withalumina as the carrier material. The disclosure of this patent is notlimited to any specific atomic ratio of gallium or indium or thallium toplatinum. No catalyst comprising tin is disclosed.

BRIEF SUMMARY OF THE INVENTION

Our invention relates to a new catalyst composition for dehydrogenatinghydrocarbons. Also, our invention relates to a process fordehydrogenating hydrocarbons using the new catalyst as well as a methodfor manufacturing the catalyst. The catalyst comprises a platinum groupcomponent, a tin component, an indium component, an alkali or alkalineearth component and a porous support material wherein the atomic ratioof indium to platinum group component is about 1.6 or higher. Thecatalyst is particularly useful for dehydrogenating detergent rangenormal paraffins (C₁₀ -C₁₅ or higher) to the corresponding normalolefins.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates normal paraffin conversion, in %, versus time, hourson stream, for the catalyst of this invention compared to representativecatalysts of the prior art. FIG. 2 illustrates selectivity to totalnormal olefins, in wt. %, versus conversion, for the same catalysts.These Figures illustrate that more conversion and more conversionstability and similar selectivity is obtained with the catalyst of thisinvention compared with the prior art catalysts.

FIG. 3 illustrates normal paraffin conversion, in %, versus time, hourson stream, for the catalyst of this invention comprising tin comparedwith other similar catalysts comprising, instead of tin, germanium andlead. This Figure illustrates the superior performance of the catalystof this invention for dehydrogenating normal paraffins compared withsimilar catalysts comprising other Group IVA metal components.

DETAILED DESCRIPTION OF THE INVENTION

Heterogeneous catalysis practice, that is, catalyzing reactions ofliquid or gaseous reactants with solid catalysts, is important toindustry. For many years persons skilled in the art of hydrocarbonconversion have endeavored to discover and develop hydrocarbonconversion catalysts with improved performance characteristics. Many ofthese persons have been highly trained in one or more of a wide varietyof disciplines including, for example, organic and inorganic chemistry,solid state and surface physics, ceramics, metallurgy and chemicalengineering. Notwithstanding this high level of skill in the art,hydrocarbon conversion catalysis, like other types of heterogeneouscatalysis, continues to be

"a vast and confusing field replete with an enormous quantity of perhapssignificant but empirical facts intermixed with perhaps useful theories.(C. N. Satterfield, Heterogeneous Catalysis in Practice, preface(1980).)

Consequently, significant contributions to the art of heterogeneoushydrocarbon conversion catalysis have generally resulted from empiricaldiscoveries and developments rather than from theoreticalextrapolations.

Our contribution to this field of art is that we have discovered a newcatalyst composition comprising a platinum group component, a tincomponent, an indium component, an alkali or alkaline earth componentand a porous support material wherein the atomic ratio of indium toplatinum group component is about 1.6 or higher. Our composition iseffective for catalyzing the dehydrogenation of dehydrogenatablehydrocarbons. The platinum group component is present in the finalcomposite in an amount, calculated on an elemental basis, of about 0.01to 5 wt. %; the tin component is present in an amount of about 0.01 to 5wt. %; the indium component is present in an amount of about 0.01 to 15wt. %; and the alkali or alkaline earth component is present in anamount of about 0.01 to 15 wt. %. For dehydrogenating detergent rangenormal paraffins (C_(1O-C) ₁₅ or higher) we have obtained best resultswhen the catalyst comprises about 0.4 wt. % platinum, about 0.5 wt. %tin, about 0.6 wt. % lithium and about 0.3 wt. % indium when the indiumcomponent is impregnated on the alumina support. The atomic ratio ofindium to platinum for this catalyst is about 1.3. We have obtained bestresults when the catalyst comprises about 0.4 wt. % platinum, about 0.5wt. % tin, about 0.6 wt. % lithium and about 1.0 wt. % indium when theindium component is cogelled with the alumina support. The atomic ratioof indium to platinum for this catalyst is about 4.2. For commercialembodiments of this invention, we plan to maintain the indium toplatinum atomic ratio at about 1.6 or higher.

Dehydrogenation conditions include a temperature of from about 400° toabout 900° C., a pressure of from about 0.1 to 10 atmospheres and aliquid hourly space velocity (LHSV--defined as the volume amount, as aliquid at standard temperature, of hydrocarbon charged to thedehydrogenation zone per hour divided by the bulk volume of a fixed bedof the catalyst utilized) of from about 0.1 to 100 hr.⁻¹. Thehydrocarbons to be dehydrogenated are dehydrogenatable hydrocarbonshaving from 2 to 20 or more carbon atoms including paraffins,alkylaromatics, naphthenes and olefins. The catalyst is particularlyuseful for dehydrogenating detergent range normal paraffins (C_(1O) -C₁₅or higher) to the corresponding normal olefins.

Our invention, then, is a new catalyst composition comprising a platinumgroup component, a tin component, an indium component, an alkali oralkaline earth component and a porous support material wherein theatomic ratio of indium to platinum group component is more than 1.0.Also, our invention is a method for converting hydrocarbons whichcomprises contacting the hydrocarbons, at hydrocarbon conversionconditions, with the catalyst of our invention. Also, our invention is away of making the catalyst.

To be commercially successful a dehydrogenation catalyst must satisfythree essential requirements, namely high activity, high selectivity andgood stability. Activity is a measure of the catalyst's ability to helpconvert reactants into products at a specified severity level whereseverity level means the reaction conditions used--that is, thetemperature, pressure, contact time and presence of diluents such ashydrogen, if any. For dehydrogenation catalyst activity we measured theconversion, or disappearance of normal paraffins, in percent relative tothe amount charged. Selectivity refers to the amount of desired productor products obtained relative to the amount of reactants charged orconverted. For catalyst selectivity we measured the amount of normalolefins in the product, in weight percent, relative to the total weightof the product. Stability refers to the rate of change with time of theactivity and selectivity parameters--the smaller rate implying the morestable catalysts. The slope of the activity versus time curve is theactivity stability, for example.

Since dehydrogenation of hydrocarbons is an endothermic reaction andconversion levels are limited by chemical equilibrium, it is desirablein order to achieve high conversion to operate at high temperatures andlow hydrogen partial pressures. Under such severe conditions it isdifficult to maintain high activity and selectivity for long periods oftime because at these conditions undesirable side reactions such asaromatization, cracking, coke formation, isomerization and poly-olefinformation increase. Therefore, there is a considerable demand for a newhydrocarbon dehydrogenation catalyst with improved activity, selectivityand stability characteristics. The catalyst of our invention, that is, acatalyst comprising a platinum group component, a tin component, anindium component and an alkali or alkaline earth component with a poroussupport material wherein the atomic ratio of indium to platinum groupcomponent is more than 1.0, will answer to such a demand.

Regarding the platinum group component of our catalyst composite, it maybe selected from the group of platinum or palladium or iridium orrhodium or osmium or ruthenium or mixtures thereof. Platinum, however,is the preferred platinum group component. We believe that substantiallyall of the platinum group component exists within the final catalyticcomposite in the elemental metallic state. Preferably the platinum groupcomponent is well dispersed throughout the catalytic composite. Theplatinum group component generally will comprise about 0.01 to about 5wt. %, calculated on an elemental basis, of the final catalyst.Preferably the catalyst comprises about 0.4 wt. % platinum.

The platinum group component may be incorporated in the catalyticcomposite in any suitable manner such as by coprecipitation orcogelation, ion exchange or impregnation, or deposition from a vaporphase or from an atomic source either before, while or after the othercatalytic components are incorporated. The preferred method ofincorporating the platinum group component is to impregnate the supportmaterial with a solution or suspension of a decomposable compound of aplatinum group metal. For example, platinum may be added to the supportby commingling the latter with an aqueous solution of chloroplatinicacid. Another acid, for example, nitric acid or another optionalcomponent may be added to the impregnating solution to further assist indispersing or fixing the platinum group component in the final catalystcomposite.

The tin component of our catalyst composite is most likely present in anoxidation state above that of the elemental metal, that is, in the +2 or+4 oxidation state as a chemical compound such as the oxide, forexample, or combined with the support material or with the othercatalyst components. Preferably, the tin component is well dispersedthroughout the catalytic composite. The tin component generally willcomprise about 0.01 to about 5 wt. %, calculated on an elemental basis,of the final catalytic composite. Preferably the catalyst comprisesabout 0.5 wt. % tin.

The tin component may be incorporated into the catalytic composite inany suitable manner, including, for example, cogelation orcoprecipitation with the support material, or ion exchange orimpregnation of the support material with a suitable tin solution orsuspension either before, while or after the other catalytic componentsare incorporated. A preferred method of incorporating the tin componentis coprecipitating it during the preparation of the support material.For example, tin may be incorporated in an alumina support material bymixing a soluble tin compound such as stannous or stannic chloride withan alumina hydrosol, adding a gelling agent and dropping the mixtureinto an oil bath to form spheres containing alumina and tin.

The indium component of our catalyst composite, like the tin component,is preferably well dispersed throughout the composite in an oxidationstate above that of the elemental metal. The indium component may bepresent as a chemical compound such as the oxide, for example, orcombined with the support material or with the other catalystcomponents. The indium component generally will comprise about 0.01 toabout 15 wt. %, calculated on an elemental basis, of the final catalyst.Preferably the catalyst comprises about 0.3 wt. % indium when the indiumcomponent is impregnated on the support material, and about 1 wt. %indium when the indium component is cogelled with the support material.About three times as much indium is required to obtain comparableresults when the indium component is cogelled with the support materialthan when it is impregnated on the support material.

The indium component may be incorporated into the catalytic composite inany suitable manner, including, for example, cogelation orcoprecipitation with the carrier material, or ion exchange orimpregnation of the carrier material with a suitable indium solution orsuspension either before, while or after the other catalytic componentsare incorporated. We have obtained good results both when the indiumcomponent has been incorporated by coprecipitating it during thepreparation of an alumina carrier material from a mixture of an aluminahydrosol, a gelling agent and a soluble indium compound such as indiumchloride or indium nitrate, for example, and by impregnating it on theprepared alumina material from a solution of indium chloride or indiumnitrate, for example.

For our catalyst, the atomic ratio of indium to platinum group componentis more than 1.0. Preferably it is more than 1.35. More preferably it ismore than 1.5. In pilot plant tests dehydrogenation catalysts withatomic ratios more than 1.0 exhibited higher stability, represented byless decrease in activity per hour on stream, than similar catalystswith atomic ratios less than 1.0.

The alkali or alkaline earth component of the catalyst of our inventionis selected from the group of cesium, rubidium, potassium, sodium andlithium or from the group of barium, strontium, calcium and magnesium ormixtures of metals from either or both of these groups. Lithium,however, is the preferred alkali or alkaline earth component. We believethe alkali or alkaline earth component exists in the catalytic compositeof my invention in an oxidation state above that of the elemental metal.The alkali or alkaline earth component may be present as a compound suchas the oxide, for example, or combined with the carrier material or withthe other components. Preferably the alkali or alkaline earth componentis well dispersed throughout the catalytic composite. The alkali oralkaline earth component generally will comprise about 0.01 to 15 wt. %,calculated on an elemental basis, of the final catalytic composite.Preferably the catalyst comprises about 0.6 wt. % lithium.

The alkali or alkaline earth component may be incorporated in thecatalytic composite in any suitable manner, for example, by cogelationor coprecipitation, by ion exchange or impregnation, or by likeprocedures either before, while or after the other catalytic componentsare incorporated. We have obtained best results when lithium has beenadded to the carrier material from an impregnating solution of lithiumnitrate.

The porous support material of the catalytic composite of our inventionis preferably a porous, absorptive support with high surface area offrom about 25 to about 500 m² /g. The porous support material should berelatively refractory to the conditions utilized in the hydrocarbondehydrogenation process. It is intended to include within the scope ofour invention the use of carrier materials which have traditionally beenutilized in hydrocarbon conversion catalysts such as, for example; (1)activated carbon, coke, or charcoal; (2) silica or silica gel, siliconcarbide, clays, and silicates including those synthetically prepared andnaturally occurring, which may or may not be acid treated, for example,attapulgus clay, china clay, diatomaceous earth, fuller's earth, kaolin,kieselguhr, etc.; (3) ceramics, porcelain, crushed firebrick, bauxite;(4) refractory inorganic oxides such as alumina, titanium dioxide,zirconium dioxide, chromium oxide, beryllium oxide, vanadium oxide,cesium oxide, hafnium oxide, zinc oxide, magnesia, boria, thoria,silica-alumina, silica-magnesia, chromia-alumina, alumina-boria,silica-zirconia, etc.; (5) crystalline zeolitic silicates such asnaturally occurring or synthetically prepared mordenite, faujasite,silicalite or other zeolites, either in the hydrogen form or in a formwhich has been exchanged with metal cations; (6) spinels such as MgAl₂O₄, FeAl₂ O₄, ZnAl₂ O₄, CaAl₂ O₄, and other like compounds having theformula MO-Al₂ O₃ where M is a metal having a valence of 2; and (7)combinations of materials from one or more of these groups. Thepreferred support material for our catalyst is alumina, especiallygamma- or eta-alu-mina.

The preferred alumina carrier material may be prepared in any suitablemanner from synthetically prepared or naturally occurring raw materials.The carrier may be formed in any desired shape such as spheres, pills,cakes, extrudates, powders, granules, etc., and it may be utilized inany particle size. A preferred form of alumina is the sphere. Apreferred particle size is about 1/16 inch in diameter, though particlesas small as about 1/32 inch, and smaller, may also be utilized.

To make alumina spheres an alumina powder is converted into an aluminasol by reacting the powder with a suitable peptizing acid and water, andthen dropping a mixture of the resulting sol and a gelling agent into anoil bath to form spherical particles of an alumina gel which are easilyconverted into the gamma-alumina carrier material by known methodsincluding aging, drying and calcining. To make alumina cylinders, analumina powder is mixed with water and a suitable peptizing agent suchas nitric acid, for example, until an extrudable dough is formed. Thedough is then extruded through a suitable sized dye to form extrudateparticles. Other shapes of the alumina carrier material may also beprepared by conventional methods. After the alumina particles are shapedgenerally they are dried and calcined. The alumina support carrier maybe subjected to intermediate treatments during its preparation,including washing with water or contacting with ammonium hydroxide, forexample, which treatments are generally well known in the art. Othercomponents may be added to the preferred alumina carrier material duringits preparation. For example, the tin component and/or the indiumcomponent can be cogelled or coprecipitated with the alumina hydrosol orthey may be added to the extrudable alumina dough, etc.

Optionally the catalytic composite of our invention may contain ahalogen component. The halogen component may be either fluorine,chlorine, bromine or mixtures thereof. Chlorine is the preferred halogencomponent. The halogen component is generally present, we believe, in acombined state with the porous carrier material. Preferably the halogencomponent is well dispersed throughout the catalytic composite. Thehalogen component, if any, generally will comprise about 0.01 to about15 wt. %, calculated on an elemental basis, of the final catalyticcomposite.

The halogen component may be added to the carrier material in anysuitable manner, either during the preparation of the support or before,while or after the other catalytic components are incorporated. Forexample, the alumina hydrosol utilized to form the preferred aluminacarrier material may contain halogen and thus contribute at least someportion of the halogen content in the final catalyst composite. Also,the halogen component or a portion thereof may be added to the catalystcomposite during the impregnation of the carrier material with the othercatalyst components, for example, by using chloroplatinic acid toimpregnate the platinum component. Also, a halogen component may beadded to the catalyst composite by adding the halogen or a compoundcontaining the halogen such as propylene dichloride, for example, to thehydrocarbon feed stream or to the recycle gas during operation of thedehydrogenation process. Or, the halogen component may also beincorporated by contacting the catalyst with the halogen or a compound,solution or suspension containing the halogen in a subsequent catalystregeneration step. In the regeneration step carbon deposited on thecatalyst as coke during use of the catalyst during the dehydrogenationprocess is burned off the catalyst and the platinum group componentwhich has become agglomerated on the catalyst is redistributed toprovide a regenerated catalyst with performance characteristics muchlike the fresh catalyst.

Optionally the catalyst composite of our invention can also contain asulfur component. Generally the sulfur component will comprise about0.01 to about 1.0 wt. %, calculated on an elemental basis, of the finalcatalytic composite. The sulfur component may be incorporated into thecatalytic composite in any suitable manner. Preferably sulfur or acompound containing sulfur such as hydrogen sulfide or a lower molecularweight mercaptan, for example, is contacted with the catalyst compositein the presence of hydrogen at a hydrogen to sulfur ratio of about 10and a temperature of from about 10° to about 540° C., preferably underwater-free conditions, to incorporate the sulfur component.

Preferably the catalyst composite of our invention is nonacidic."Nonacidic" in this context means that the catalyst has very littleisomerization activity, that is, the catalyst converts less than 10 mole% of 1-butene to isobutylene when tested at dehydrogenation conditionsand, preferably, converts less than 1 mole %. The acidity of thecatalyst can be minimized to make the catalyst nonacidic by increasingthe amount of the alkali or alkaline earth component and/or byminimizing the amount of the halogen component. The amount of halogencomponent can be minimized by subjecting the catalyst composite to atreatment with high temperature steam or a mixture of steam and adiluent gas such as air or hydrogen or nitrogen.

After the catalyst components have been combined with the porous carriermaterial, the resulting catalyst composite will generally be dried at atemperature of from about 100° to about 320° C. for a period typicallyof about 1 to about 24 hours or more and thereafter calcined at atemperature of about 320° to about 600° C. for a period of about 0.5 toabout 10 or more hours. The acidity of the catalyst composite ispreferably adjusted during or after the calcination step by treating thecalcined composite with high temperature steam or with a mixture ofsteam and a diluent gas in the manner described earlier. Finally thecalcined and possibly acid adjusted catalyst composite is typicallysubjected to a reduction step before use in the dehydrogenation process.Preferably, a substantially pure and dry hydrogen stream is used as thereducing agent in this step. This reduction step is effected at atemperature of about 230° to about 650° C. for a period of about 0.5 toabout 10 or more hours, the temperature and time being selected to belong and hot enough to reduce substantially all of the platinum groupcomponent to the elemental metallic state.

According to the method of the present invention the dehydrogenatablehydrocarbons are contacted with the catalytic composite of our inventionin a dehydrogenation zone maintained at dehydrogenation conditions. Thiscontacting may be accomplished in a fixed catalyst bed system, a movingcatalyst bed system, a fluidized catalyst bed system, etc., or in abatch type operation. A fixed bed system is preferred. In this fixed bedsystem the hydrocarbon feed stream is preheated to the desired reactiontemperature and then passed into the dehydrogenation zone containing afixed bed of the catalyst. The dehydrogenation zone may itself compriseone or more separate reaction zones with heating means therebetween toinsure that the desired reaction temperature can be maintained at theentrance to each reaction zone. The hydrocarbon, preferably in the vaporphase, although it may be in a mixed vapor-liquid phase or in the liquidphase, may be contacted with the catalyst bed in either upward, downwardor radial flow fashion. Radial flow of the hydrocarbon through thecatalyst bed is preferred for commercial scale reactors.

Conditions in the dehydrogenation zone include a temperature of fromabout 400° to about 900° C., a pressure of from about 0.1 to 10atmospheres and a liquid hourly space velocity (LHSV) of from about 0.1to 100 hr.⁻¹. Generally, for normal paraffins the lower the molecularweight of the hydrocarbon the higher the temperature required forcomparable conversion. The pressure in the dehydrogenation zone ismaintained as low as practicable, consistent with equipment limitations,to maximize the equilibrium advantages.

The effluent stream from the dehydrogenation zone generally will containunconverted dehydrogenatable hydrocarbons, hydrogen and the products ofdehydrogenation reactions. This effluent stream is typically cooled andpassed to a hydrogen separation zone to separate a hydrogen-rich vaporphase from a hydrocarbon-rich liquid phase. Generally, thehydrocarbon-rich liquid phase is further separated by means of either asuitable selective adsorbent, a selective solvent, a selective reactionor reactions or by means of a suitable fractionation scheme. Unconverteddehydrogenatable hydrocarbons are recovered and may be recycled to thedehydrogenation zone. Products of the dehydrogenation reactions arerecovered as final products or as intermediate products in thepreparation of other compounds.

The dehydrogenatable hydrocarbons may be admixed with a diluent materialprior, while or after being passed to the dehydrogenation zone. Thediluent material may be hydrogen, steam, methane, ethane, carbon dioxideand the like. Hydrogen is the preferred diluent. Ordinarily, whenhydrogen is utilized as the diluent it is utilized in amounts sufficientto insure a hydrogen to hydrocarbon mole ratio of about 1:1 to about40:1, with best results being obtained when the mole ratio range isabout 1.5:1 to about 10:1. The diluent hydrogen stream passed to thedehydrogenation zone will typically be recycled hydrogen separated fromthe effluent from the dehydrogenation zone in the hydrogen separationzone.

Water or a material which decomposes at dehydrogenation conditions toform water such as an alcohol, aldehyde, ether or ketone, for example,may be added to the dehydrogenation zone, either continuously orintermittently, in an amount to provide, calculated on the basis ofequivalent water, about 1 to about 20,000 wt. ppm of the hydrocarbonfeed stream. About 1 to about 10,000 wt. ppm of water addition givesbest results when dehydrogenating detergent range normal paraffins.

The following worked Examples are introduced to describe further thecatalyst of our invention and to teach one skilled in the art how tomake it and how to use it in the dehydrogenation process of ourinvention. These Examples represent specific embodiments of ourinvention and are intended to be illustrative only and not restrictive.

EXAMPLE I

A catalyst composite, hereinafter catalyst "A", was prepared torepresent the catalyst of our invention. The catalyst comprised about0.4 wt. % platinum, about 0.5 wt. % tin, about 0.3 wt. % indium andabout 0.6 wt. % lithium on a carrier of gamma-alumina. The atomic ratioof indium to platinum for this catalyst was 1.27. The catalyst wasprepared by dissolving substantially pure aluminum pellets in ahydrochloric acid solution, thereafter dissolving in this sol an amountof stannic chloride calculated to provide a final composite containingabout 0.5 wt. % tin, and then stirring the sol vigorously to distributethe tin component evenly throughout it. Hexamethylenetetramine was thenadded to the sol and the resulting mixture was dropped into an oil bathin a manner to form spherical particles having an average particlediameter of about 1/16 inch. Thereafter the spheres were aged and washedwith an ammoniacal solution, then dried and calcined to form a sphericalgamma-alumina carrier material containing about 0.5 wt. % tin in theform of tin oxide. More details about this method of preparing thepreferred alumina carrier material are disclosed in U.S. Pat. No.2,620,314.

Then, 90 g (300 cc) of the tin-containing alumina carrier was contactedwith 300 cc of a solution of 0.6 g of indium nitrate dissolved in 3.2 ccof 70.8% nitric acid, 5.4 g of lithium nitrate and water in a rotarydrier at room temperature under nitrogen for 15 minutes. Then steam waspassed to the jacket of the drier and the water was driven off, leavingthe indium and lithium components incorporated with the tin-containingalumina carrier. This composite was then calcined in a quartz tubefurnace at 550° C. with 300 hr.⁻¹ gas hourly space velocity(GHSV--defined as the volume amount, as gas at standard temperature andpressure, of treating gas charged to the calcination zone per hourdivided by the bulk volume of the catalyst being calcined) of a 50/50air/80° C. steam mixture for 6 hours. Then, the tin, indium, lithium andalumina composite was contacted with 300 cc of a solution of 7.5 cc of0.452 g/cc chloroplatinic acid solution and 3.2 cc of 70.8% nitric acidand water in a rotary drier at room temperature under nitrogen for 15minutes. Then, this mixture was also steamed to dryness, and calcined at540° C. with 300 hr.⁻¹ gas hourly space velocity (GHSV) of a 50/50air/80° C. steam mixture for 2 hours. This catalyst "A" and,alternatively, catalyst "D" in Example 2, represent preferredembodiments of my catalytic composite.

A different prior art catalyst, hereinafter catalyst "B", was preparedto represent the dehydrogenation catalyst disclosed in U.S. Pat. No.3,745,112. This catalyst comprised 0.4 wt. % platinum, 0.5 wt. % tin and0.6 wt. % lithium. It was prepared in the same manner as catalyst "A"above, except the indium component, required for the catalyst of ourinvention, was not added to catalyst "B".

Another different prior art catalyst, hereinafter catalyst "C", wasprepared to represent one of the dehydrogenation catalysts disclosed inBritish Pat. No. 1 499 297. This catalyst comprised 0.4 wt. % platinum,0.3 wt. % indium and 0.54 wt. % lithium. It was prepared in the samemanner as catalyst "A" above, except that the tin component required forthe catalyst of our invention, was not added to catalyst "C".

All of these catalysts contained a small amount of sulfur componentwhich was incorporated in a sulfiding step at 485° C. and 1 atmospherepressure from a 1% mixture of hydrogen sulfide in hydrogen gas at 3,100hr.⁻¹ gas hourly space velocity (GHSV) for 5 hours. After the sulfidingstep these catalysts contained approximately 0.1 wt. % sulfur,calculated on an elemental basis.

All of these catalysts were reduced in a reduction step prior to beingtested. Reduction conditions were; 485° C. and 1 atmosphere presssure inhydrogen gas at 7,900 hr.⁻¹ GHSV for 1 hour.

These catalysts were all tested for dehydrogenation activity,selectivity and stability in a laboratory scale dehydrogenation plantcomprising a reactor, a hydrogen separation zone, and heaters, coolers,pumps, compressors, and the like conventional equipment for handlinghydrocarbons. In this plant, the feed stream containing thedehydrogenatable hydrocarbon is combined with a hydrogen gas stream andthe resulting mixture is heated to the desired conversion temperaturewhich is measured at the inlet to the dehydrogenation reactor. Theheated mixture then contacts the fixed bed of catalyst in downflowfashion. The pressures reported herein are measured at the outlet fromthe reactor. An effluent stream is withdrawn from the reactor, cooled,and passed into the hydrogen separation zone to separate a hydrogen-richgas phase from the hydrocarbon-rich liquid phase. The hydrocarbon-richliquid phase is withdrawn from the hydrogen separation zone and analyzedto measure the amount of conversion, or activity, and the relativeamount of desired dehydrogenated hydrocarbons, or selectivity, for thecatalyst composite being tested. Conversion numbers reported herein arecalculated on the basis of disappearance of normal paraffins, expressedin wt. %, of the feed stream. Similarly, selectivity numbers reportedare calculated on the basis of desired normal olefins produced,expressed in wt. %, of the liquid product recovered.

The same normal paraffin feed stream was used in all the tests. Itcomprised in wt. %;

n-Decane: 0.3

n-Undecane: 28.5

n-Dodecane: 35.8

n-Tridecane: 26.7

n-Tetradecane: 8.0

Total Linear Paraffins: 99.3

Total Non-Linear Paraffins: 0.7

Reaction conditions were generally the same for all tests. They were;485° C., 2.4 atmospheres, 6 hydrogen to hydrocarbon mole ratio, 20 hr.⁻¹liquid hourly space velocity (LHSV) for the tests of catalysts "B" and"C", and 17 hr.⁻¹ LHSV for the test of catalyst "A". In our opinion, theslightly lower LHSV for the test of catalyst "A" did not substantiallyeffect the comparison of catalyst "A" with catalysts "B" and "C" asreported. Results from the tests are presented in FIGS. 1 and 2.

FIG. 1 clearly shows that the catalyst of our invention, catalyst "A"comprising platinum, tin, indium and lithium, possesses superioractivity and activity stability compared to the prior art catalyst "B"comprising platinum, tin and lithium, but without indium, and comparedto the prior art catalyst "C" comprising platinum, indium and lithium,but without tin. FIG. 2 shows that the selectivity and selectivitystability of our catalyst "A" is comparable to the best of these priorart catalysts.

EXAMPLE II

A catalyst composite, hereinafter catalyst "D", was prepared torepresent the catalyst of our invention. The catalyst comprised about0.4 wt. % platinum, about 0.5 wt. % tin, about 1.3 wt. % indium andabout 0.6 wt. % lithium on a carrier of gamma-alumina. The atomic ratioof indium to platinum for this catalyst was 5.52. The alumina carriermaterial for this catalyst was prepared in the same manner as forcatalyst "A" in Example I above, except the indium component wasincorporated by dissolving an amount of indium nitrate, calculated toprovide a final composite containing about 1.0 wt. % indium, in thealumina sol. Then 24 g (100 cc) of the tin and indium-containing aluminacarrier was contacted with 100 cc of a solution of 0.10 g of platinumfrom chloroplatinic acid, 0.15 g of lithium from lithium nitrate, 0.75 gof nitric acid and water in a rotary drier at room temperature undernitrogen for 15 minutes. Then the mixture was dried, leaving theplatinum and lithium components incorporated with the tin andindium-containing alumina carrier. This composite was then calcined inair for 1 hour at 540° C., with the warm-up from room temperature andthe cool-down to room temperature in nitrogen.

A different catalyst, hereinafter catalyst "E", comprising 0.4 wt. %platinum, 0.3 wt. % germanium, 1.1 wt. % indium and 0.6 wt. % lithiumwas prepared in the same manner as catalyst "D" above, except germanium,in the form of germanium chloride, was added to the alumina sol insteadof tin.

Another different catalyst, hereinafter catalyst "F", comprising 0.4 wt.% platinum, 0.8 wt. % lead, 1.0 wt. % indium and 0.6 wt. % lithium wasprepared in the same manner as catalyst "D" above, except lead, in theform of lead aftate, was added to the alumina sol instead of tin.

These catalysts were not subjected to the sulfiding step utilized in thetests of the catalysts "A", "B" and "C" in Example I. These catalystswere reduced in the same manner as the catalysts in Example I, however.

The same feed stream and reaction conditions utilized in Example I werealso utilized to test these catalysts, except the LHSV for all of thesecatalysts was 28 hr.⁻¹. In our opinion, the slightly higher wt. % ofindium in catalyst "D" did not substantially effect the comparison ofcatalyst "D" with catalysts "E" and "F" as reported. Results from thetests are presented in FIG. 3.

FIG. 3 clearly shows that the catalyst of our invention, catalyst "D"comprising platinum, tin, indium and lithium, possesses superioractivity and activity stability compared to similar catalysts "E" and"F" comprising, instead of tin, other Group IVA metals, namely germaniumand lead, respectively.

EXAMPLE III

We studied the effect of the indium to platinum group component atomicratio on the activity stability of dehydrogenation catalysts comprisinga platinum group component, a tin component, an indium component, analkali or alkaline earth component and a porous support material. Fivecatalysts were prepared generally in the same manner as for catalysts inthe preceding EXAMPLES. Catalyst "G" comprised 0.364 wt. % platinum, 0.5wt. % tin and 0.6 wt. % lithium. This catalyst contained no indiumcomponent. Catalyst "H" comprised 0.366 wt. % platinum, 0.5 wt. % tin,0.11 wt. % indium and 0.6 wt. % lithium. Catalyst "I" comprised 0.375wt. % platinum, 0.5 wt. % tin, 0.26 wt. % indium and 0.6 wt. % lithium.Catalyst "J" comprised 0.386 wt. % platinum, 0.5 wt. % tin, 0.34 wt. %indium and 0.6 wt. % lithium. Catalyst "K" comprised 0.415 wt. %platinum, 0.5 wt. % tin, 0.39 wt. % indium and 0.6 wt. % lithium. Allthese catalysts were sulfided to a level of about 0.1 wt. % sulfur.

These catalysts were tested for dehydrogenation of normal C₁₁ -C₁₄paraffins in a laboratory plant like the one described in EXAMPLE I. Thefeed stream comprised in wt. %:

n-Decane: 0.3

n-Undecane: 28.6

n-Dodecane: 35.7

n-Tridecane: 26.6

n-Tetradecane: 8.1

Reaction conditions, which were the same for all tests, were: 485° C.,2.4 atmospheres, 6 hydrogen to hydrocarbon mole ratio and 20 hr.⁻¹ LHSV.2,000 wt. ppm water was added to the dehydrogenation zone. In ouropinion, the slightly higher wt. % platinum for catalysts "H", "I", "J"and "K" did not substantially effect their comparison with catalyst "G"as reported. Results from the tests are summarized in TABLE I.

                  TABLE I                                                         ______________________________________                                                                Relative                                              Catalyst  In/Pt Atomic Ratio                                                                          Activity Stability                                    ______________________________________                                        G         0             1.0                                                   H         0.51          1.14                                                  I         1.18          1.39                                                  J         1.50          1.61                                                  K         1.60          4.0                                                   ______________________________________                                    

From TABLE I it is apparent that dehydrogenation catalysts with addedindium component exhibited higher activity stability than a referencecatalyst without indium. Furthermore, the beneficial effect of indiumwas realized for catalysts with indium to platinum ratios more than 1.0.Best stability was obtained for the catalysts with the highest indium toplatinum ratios.

We claim as our invention:
 1. A catalyst composition comprising aplatinum group component, a tin component, an indium component, analkali or alkaline earth component and a porous support material whereinthe atomic. ratio of indium to platinum group component is about 1.6, orhigher.
 2. The catalyst of claim 1 wherein the platinum group componentcomprises platinum.
 3. The catalyst of claim 1 wherein the alkali oralkaline earth component comprises lithium.
 4. The catalyst of claim 1wherein the porous support material is alumina.
 5. The catalyst of claim1 which comprises, calculated on an elemental basis, about 0.01 to 5 wt.% platinum group component, about 0.01 to 5 wt. % tin, about 0.01 to 15wt. % indium and about 0.01 to 15 wt. % alkali or alkaline earthcomponent.
 6. The catalyst of claim 1 which comprises about 0.01 toabout 15 wt. % halogen component.
 7. The catalyst of claim 1 whichcomprises about 0.01 to about 1.0 wt. % sulfur component.
 8. A catalystcomposition comprising a platinum group component, a tin component, anindium component, an alkali or alkaline earth component and a poroussupport material wherein the atomic ratio of indium to platinum groupcomponent is about 1.6, or higher, said catalyst being nonacidic.
 9. Amethod for making a catalyst which comprises incorporating a platinumgroup component, a tin component, an indium component and an alkali oralkaline earth component with a porous support material so that theatomic ratio of indium to platinum group component is about 1.6, orhigher.
 10. The method of claim 9 wherein the indium component isimpregnated on the support material.
 11. The method of claim 9 whereinthe indium component is cogelled with the support material.